#define _CRT_SECURE_NO_WARNINGS 
#include<stdio.h>
#include<iostream>
using namespace std;

class area_cl
{
protected:
	double height;
	double width;

public:
	area_cl(double r, double s)
	{
		height = r;
		width = s;
	}
	virtual double area() = 0;

};

class rectangle
{
protected:
	double height;
	double width;

public:
	rectangle(double r=1, double s=1)
	{
		height = r;
		width = s;
	}
	double area
	{
		return r * s;
	}
};

class isosceles
{
protected:
	double height;
	double width;

public:
	isosceles(double r = 1, double s = 1)
	{
		height = r;
		width = s;
	}
	double area
	{

		return ((r * s)/2.0);
	}

};